REFRESH CONTROL UNIT
7-8
7.7.2.1
Refresh Base Address Register
The Refresh Base Address Register (Figure 7-6) programs the base (upper seven bits) of the re-
fresh address. Seven-bit mapping places the refresh address at any 4 Kbyte boundary within the
1 Mbyte address space. When the partial refresh address from the 9-bit address counter (see Fig-
ure 7-1 and “Refresh Control Unit Capabilities” on page 7-2) passes 1FFH, the Refresh Control
Unit does not increment the refresh base address. Setting the base address ensures that the address
driven during a refresh bus cycle activates the DRAM chip select.
Figure 7-6. Refresh Base Address Register
7.7.2.2
Refresh Clock Interval Register
The Refresh Clock Interval Register (Figure 7-7) defines the time between refresh requests. The
higher the value, the longer the time between requests. The down-counter decrements every fall-
ing CLKOUT edge, regardless of core activity. When the counter reaches one, the Refresh Con-
trol Unit generates a refresh request, and the counter reloads the value from the register. Since
Power-Save mode divides the clock to the Refresh Control Unit, this register will require repro-
gramming if Power-Save mode is used.
Register Name:
Refresh Base Address Register
Register Mnemonic:
RFBASE
Register Function:
Determines upper 7 bits of refresh address.
Bit
Mnemonic
Bit Name
Reset
State
Function
RA19:13
Refresh
Base
00H
Uppermost address bits for DRAM refresh
cycles.
NOTE:
Reserved register bits are shown with gray shading. Reserved bits must be written
to a logic zero to ensure compatibility with future Intel products.
15
0
R
A
1
3
R
A
1
4
R
A
1
5
R
A
1
6
R
A
1
7
R
A
1
8
R
A
1
9
A1503-0A
Содержание 80C186XL
Страница 1: ...80C186XL 80C188XL Microprocessor User s Manual...
Страница 2: ...80C186XL 80C188XL Microprocessor User s Manual 1995...
Страница 18: ...1 Introduction...
Страница 19: ......
Страница 27: ......
Страница 28: ...2 Overview of the 80C186 Family Architecture...
Страница 29: ......
Страница 79: ......
Страница 80: ...3 Bus Interface Unit...
Страница 81: ......
Страница 127: ......
Страница 128: ...4 Peripheral Control Block...
Страница 129: ......
Страница 137: ......
Страница 138: ...5 ClockGenerationand Power Management...
Страница 139: ......
Страница 154: ...6 Chip Select Unit...
Страница 155: ......
Страница 178: ...7 Refresh Control Unit...
Страница 179: ......
Страница 193: ......
Страница 194: ...8 Interrupt Control Unit...
Страница 195: ......
Страница 227: ......
Страница 228: ...9 Timer Counter Unit...
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Страница 254: ...10 Direct Memory Access Unit...
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Страница 284: ...11 Math Coprocessing...
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Страница 302: ...12 ONCE Mode...
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Страница 306: ...A 80C186 Instruction Set Additions and Extensions...
Страница 307: ......
Страница 318: ...B Input Synchronization...
Страница 319: ......
Страница 322: ...C Instruction Set Descriptions...
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Страница 371: ......
Страница 372: ...D Instruction Set Opcodes and Clock Cycles...
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Страница 396: ...Index...
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